Among conventional outboard motors, steering apparatuses comprising a steering plate and a steering rod are known, such as the one disclosed in Japanese Patent Application Laid-Open Publication No. 5-319387 (H05-319387 A), for example. FIGS. 7 and 8 hereof show the steering apparatus disclosed in H05-319387A.
Referring to FIG. 7, in a steering apparatus 200, a steering cable 201 is moved by turning a steering handle left and right. A linking member 202 linked to the steering cable 201 then moves left and right as shown by the arrow (1), and a steering rod 203 connected to the end of the linking member 202 moves as shown by the arrow (2). The distal end of a steering plate 204 is pushed and pulled by the steering rod 203, and the steering plate 204 swings left and right about a swivel shaft 205 as shown by the arrow (3). As a result, an outboard motor body connected to a rear end part 206 of the steering plate 204 is steered, and an operator can steer the outboard motor.
A connecting hole 208 of the steering rod 203 is formed on a center line 207 of the steering plate 204 as shown in FIG. 8. The connecting hole 208 traverses an arc 209 of a radius R centered on the swivel shaft 205.
The symbol α1 represents the steering angle when the linking member 202 is moved in the same distance either to the left or right from a neutral position shown by the solid line and the steering plate 204 is swung far to the left or right. In this example, α1=50°. The center line 207 passes through the center of the swivel shaft 205. The linked portion between the linking member 202 and the steering rod 203 constitutes a linking point 210, the linked portion between the steering rod 203 and the steering plate 204 constitutes a linked point 211, and a straight line joining the connecting point 210 and the connecting point 211 is designated as a straight line 212.
The symbol β1 represents the angle formed by the center line 207 and the straight line 212 when the steering plate 204 has swung to the left from its neutral position in a vertical state, and the symbol β2 represents the angle formed by the center line 207 and the straight line 212 when the steering plate 204 has swung to the right.
When the outboard motor is steered, the linked point 211 bears a force F1 tangential to the arc 209 whether the outboard motor is steered to the left or right. Given that S1 represents the force of the steering rod 203 pushing on the steering plate 204 when the outboard motor is steered to the left and S2 represents the force of the steering rod 203 pulling on the steering plate 204 when the outboard motor is steered to the right, β1<β2, and therefore S1>S2. Specifically, the steering load is greater when steering is to the left than when steering is to the right. In other words, there is a disparity in steering loads between left steering and right steering.